Steerable antenna system



jan 6, 1942 F. A. POLKINGHORN 226,44;

' STEERABLE ANTENNA SYSTEM Filed Feb. 17, 1940 2 Sheets-Sheet lADJUSTABLE DE L A y #24ML ATOR DE VICE PHASE SPL/7' TE l? PHASEJPL/T'TEI? /M/ENTOR E A. POL/f/A/GHORA/ ATTnDA/EV Jam., 6, 1942. F. A.POLKINGHORN 2,2%,344

S TEERABLE ANTENNA S YS TEM comme@ PHASE smi /A/L/EA/Ton FA.POL/(INGHOR/V Patented Jan. 6, 1942 seras ,caen

T @ENCE STEERABLE ANTENNA SYSTEM Application February 17, 1940, SerialNo. 319,394

7 Claims.

This invention relates to phase control circuits and more particularlyto multichannel phase control circuits especially adapted for use insystems having a plurality of input circuits and one or more outputcircuits.

As disclosed in Patent 2,041,600, H. T. Friis, May 19, 1936, highlyeicient radio reception or transmission may be secured utilizing anarray comprising a plurality of antenna units connected throughadjustable individual phase shifters to the receiver. In this system ormethod the phases o'f the antenna currents are adjusted for the purposeof aligning the maximum directive lobe of the array with the optimumdirection of vtransmission or'reception, and it has been suggested thata phase shifter of the type illustrated by Fig. 1 of Patent 2,147,728,W. T. Wintringham, February 21, 1939, and comprising a variablecondenser and a phase splitting network included between each antennaunit and associated condenser, be employed in order to secure anaccurate phase and amplitude control and a constant uniform loss in thephase shifter with adjustment of phase. Thus, in a large practicalreceiving system comprising sixteen antenna units and sixteen phaseshifting variable condensers, sixteen phase splitting networks would beutilized. 'If reception is desired over several paths or diversitybranches a group of sixteen condensers is required for each diversitybranch and several conde'nsers, one for each diversity branch, may beconnected to the output terminals of the phase splitting networkassociated with each unit. It now appears desirable to simplify greatlythe phase control arrangement described above and particularly toachieve a substantial reduction in cost, both in initial and maintenanceexpense, for multichannel control circuits used in a multiunit steerablearray, hereinafter referred' to simply as MUSA, comprising a largenumber of antenna units. More particularly it appears desirable toemploy a minimum number of networks in receiving systems comprising agiven plurality of antenna units or input circuits and a differentplurality of diversity branches cr output circuits.

It is one object of this invention to control the phase relation ofseveral currents in a simple and economical manner.

It is another object of this invention to utilize a minimum amount ofequipment for adjusting or controlling, without change of amplitude, thephase relation of several currents.

It is still another object of this invention to steer or adjust foroptimum operation one or more directive characteristics of a multiunitantennaarray without attenuating upon change of adjustment the antennacurrents, and utilizing a minimum amountof equipment.

It is a further object of this invention to 'control, in a transmissionsystem included between a plurality of input circuits or energy sourcesand a plurality of outputnircuits or load devices and comprising aplurality of distinct transmission paths, the phase relation of thecurrents in an eiicient and inexpensive manner.

According to this invention, in a system having a plurality of inputcircuits and one or more output circuits vand employing phase controlcircuits of the type described above, a minimum number of networks maybe utilized when the number of input 'circuits exceeds the number ofoutput circuits, by including a phase combining network between eachoutput circuit and a separate set of condensers connected to the inputcircuits; and, when the number of output circuits is greater than thenumber of input circuits, by connecting a phase splitting networkbetween each input circuit anda separate set of condensers connected tothe output circuits. When the number of input circuits and the number ofoutput circuits are equal either arrangement may be utilized. Thus, in afour-angle diversity MUSA system comprising sixteen antenna units andsixty-four control condensers, four control networks may be employedinstead of sixteen as previously suggested.

The invention will be more fully understood from a perusal of thefollowing specification taken in conjunction with the drawings in whichlike reference characters denote elements of similar function and inwhich:

Fig, 1 illustrates a-two-angle diversity, threeunit MUSA system arrangedin accordance with prior art suggestions;

Fig. 2 illustrates a two-diversity, three-unit MUSA system constructedin accordance with the invention; and

Fig. 3 illustrates an embodiment of the invention as incorporated in alarge MUSA system.

Referring to Fig. 1, reference numerals I designate antenna-counterpoiseunits which may each have a directive characteristic or a nondirectivecharacteristic and which together constitute an array for receiving anincoming signal over the two diversity paths or branches A and B, theunits being spaced along the array axis 2. Each unit is coupled throughinput transformer 3 or 4 or 5, to the input terminals 6 and `l of aphase splitting network having four `2| through the receiver 39.

cuits 3, 4` and 5 are connected to the two outputy eachr antenna and theassociated transformer 3, Iy Reference numerals 24 designatephasecontrolvariable condensers for diversity branch A, eachof thesecondensers having a rotor v25 and four stator plates 26, 21, 28 and 29which are connected, respectively, to network terminals,

I0, and rI2 through conductors 30. VA similar set of Vthree condensers3|, one foreach input circuit, is provided for. diversity branch B, the

32 to thestators of the condenser 24 and to the sion channels as thesystem of Fig. 1,` it will be i seen that in accordance with theinvention the connections for each variable condenser are reversed withrespect to those in the system of Fig. 1, and that instead of phasesplitting networks, one for each input circuit, phase combiningnetworks, one for each output circuit, are utilized.

The phase combining networks 42 are the samein construction as the phasesplittingnetwork 8 of Fig. 1. Thus considering each diversity branch oroutput circuit and the three condensers therefor, the input circuits 3,4 and 5 are each con-r nected to the rotors 25 and the stators areconstators ofy each being connected by conductors four terminals-of thenetwork 8 associated with the samefinput circuit or antenna. ofcondensers 24 and 3| and the associated phase splitting networkconstitutes a distinct phase control circuit.

The rotors 25 of condenser 24 for diversity branch A are connected`together by conductor y33 and through adjustable `delay device 34 to theinput terminal or circuit 35 vby means of con-- ductorsSBf; and the.rotors 25 of condensers 3| together and directly connected to outputterminal 3.1. `Therctors for the condensers in each Thus, each rnectedthrough a single combining network to the output circuit; whereas inFig. `l, the input circuitsare connected through separate splitting ,Ynetworks tothe stators and the rotors are connected to the outputcircuit. It maybe noted herethat each condenser and associated network,as used in the systems of Figs. 1 `and 2, constitute a passive network,and, as is known, the

`output and input .terminals of such a network` `may be-interchanged.More particularly, referring to Fig. `2, the secondary windings oftransformers 3, 4 and 5 are each connected by a conductor-40 to therotors 25 of a condenser and a condenser 3 I; and the stators 2B and 21,28 and f 29` of. rthe three condensers in each diversity groupareconnected by the conductors, re-

f for diversity branch B are similarly connected spectivelyto theterminals 9, I0, and |2fof a network` 42, each network comprisingcondensers I3 and v|4condensers I5 and I6, coils I1 and- III diversitybranch arer preferably unicontrolled through graded gears, in accordancewith the disclosure in ther above-mentioned Friis patent,

as indicated schematically by line 38. The outf put terminals 35 and 31are connected to ground Hence, input circircuits 35 and 31 through asix-channel transmission system each including a phase controlcondenser. It should be noted that the phase control networks aredirectly associated with the input circuits, and that the number ofnetworks is equal to the number of input circuits and greater than thenumber of output circuits.

In operation, the components of a desired wave as received Iover the twopaths A and B on the several antennas are conveyed through transformers3, 4 and 5 to the input terminals 6 and I of each of the three networks8. As explained in the Friis patent mentioned above, the componentsintercepted by adjacent units differ in phase by an amount related tothe wave arrival angle A or B. Since the network 8 is in effect aquadrature phase shifter, each network functions to impress quadraturepotentials `on the four stator plates of each condenser 24 and 3|associated therewith, whereby the potential impressed on the condenserrotor 25 mayvhave any phase and is determined solely by the rotorposition. As ordinarily used therotors 25 of condensers 24 aresimultaneously adjusted so as to secure thereon in-phase potentials forwaves having the incoming direction A; and the rotors 25 of condenser 3|are similarly adjusted to secure in-phase potentials for componentsfollowing direction B. Delay device 34 is then adjusted for the purposeof rendering the output potentials or the currents for the two branchesin phase agreement on terminals 35 and 37.

Referring now to Fig. 2 which illustrates a multi-channel system havingthe same number of input circuits, output circuits and transmisand aresistance I9. The output terminals 43 and v|4of eachv network 42 areconnected to the receiver 39 by line 45, a delay device'34 beingincluded in branch A between the phase combiningnetwork 42 and thereceiver 39. Thus, as in the system` of Fig. 1 the transmission systemcomprises six channels and each condenser and associated networkconstitute a phase control circuit. f

In operation, out-of-phase wave components received over each of paths Aand B by the antenna units are impressed on the rotors 25 of thecondensers 24 and on the rotors of condensers 3|. The rotors ofcondensers 24 and the rotors of condensers 3| are adjusted so thatin-phase potentials are secured, respectively, for directions A and B onthe output terminals of the respective network 42. More specifically,the rotors 25 of condensers 24 are adjusted so that the out-ofphasepotentials impressed thereon by the antenna units produce in-phasepotentials on the output terminals 43 and 44 of the network for waveshaving the direction A and the rotors 24 of condensers 3| are adjustedto secure in-phase output potentials for a wave having direction B. Asin the circuit of Fig. 1, the delay circuit 34 is then adjusted so thatthe energies received over branches A and B are rendered in phaseagreement before being supplied to the receiver 39. In a sense, in thesystem of Fig. 1, each rotor selects from the phase splitter terminals aproperly phased potential whereas, in the system of Fig.` 2, each rotorimpresses on the phase combiner terminals properly phased potentials.

It is therefore apparent that, in accordance with the invention, areduction in the number of networks required is realized, the numberbeing equal to either the number of input circuits or the number ofoutput circuits, whichever is smaller. Comparing the prior art system ofFig. 1 with applicants system, Fig. 2, each system having three inputand two output circuits, three networks are used in the prior artarrangement whereas only two networks are employed in applicants system.Ordinarily in steerable antenna, systems of the type referred to abovethe number of input circuits exceeds the number of output circuits, and,in accordance with the invention, a considerable economical saving iseffected.

Fig. 3 illustrates a large practical MUSA system especially suited fortransoceanic communication and designed for four-angle diversityreception. The system comprises sixteen highly unidirectional rhombicantennas 5| spaced along the array axis 52 and connected each through atransformer 53 to the rotors 25 of Ifour condensers 54, 55, 56 and 5l,each of the four condensers being included in a different diversitybranch. Thus, sixteen -condensers 54 are provided for branch A, sixteencondensers 55 for branch B, sixteen condensers 56 for branch C andsixteen condnsers 51 for branch D. As in Fig. 2, the stators 26, 21, 28and 29 for the condensers for each branch are connected by conductors 4|in parallel and to the four terminals of a phase combining network 42one of which is provided `for each branch. The output terminals 43 and44 of all networks, except the network 2 for branch D, are connected bylines 45 through a separate delay device 34 to the input terminals ofreceiver 39. The network l2 for branch D is directly connected to thereceiver 39. If desired, one of the sets of sixteen condensers andassociated network may be used for monitoring purposes instead of forservice reception, as disclosed in Patent 2,173,858 of N. J. Pierce andF. A. Polkinghorn, granted September 26, 1939.

The directive operation of the MUSA system of Fig. 3 is fully explainedin the Friis patent. Moreover, in vie-w of the discussion given above inconnection with Fig. 2, the operation of the phase control multichannelsystem of Fig. 3 is believed to be apparent. It should be noted thatwhile sixteen input circuits or antenna units, four output circuits orbranches and sixty-four variable condensers are utilized only fourcontrol networks are employed, whereas if the arrangement illustrated byFig. 1 were utilized, sixteen networks, each relatively expensive bothin structural cost and installation cost, would be required. It may beadded that, as described in the abovementioned patent ofPierce-Polkinghorn, the receiver 39 in network 52 may be located at thecenter of the array and the two halves of the array may, if desired, beseparately or jointly used. In this case each subarray of eight antennaunits would require four phase combining networks, and for the wholesystem, a saving of eight networks would be realized as compared to theprior art arrangement. It should be added also that the invention isequally suited for use in transmitting and receiving systems and may beused i'n MUSA systems arranged for directive steering in a plurality ofplanes.

Although the invention has been described in connection with certainembodiments, it should be understood that it is not to be limited to theembodiments described since other apparatus may be successfully employedwithout exceeding the scope of the invention. Thus, the number of statorplates in each variable phase shifting condenser may be other than four,as for example, eight; and again, instead of a variable condenser avariable inductance may be satisfactorily employed in each phase controlcircuit.

What is claimed is:

1. In an electrical system, a plurality of energy sources each connectedthrough a separate transmission channel to a load circuit and means foradjusting with uniform loss the phase relation of the currents in saidchannels, said means comprising a variable phase splitter included ineach channel for deriving from the channel current two sets of oppositephase components, and a common phase combiner included between all ofsaid phase splitters and said load circuit and, comprising a phaseshifter for changing the phase relation between the two sets ofcomponents in each channel.

2. In a radio system, an antenna array comprising a plurality of antennaunits, a translation device, a set of adjustable phase changers eachhaving a constant loss with adjustment, each changer comprising anindividual variable condenser having a rotor connected to a diierentantenna unit and four stator plates, a common@ quadrature phase shifterconnected to the translation device and having four terminals eachconnected to a different set of corresponding stator plates.

3. In an angle diversity radio receiving system, a multiunit steerableantenna array, a receiver and a set of adjustable phase changers foreach diversity branch, each changer having uniform loss with adjustmentand each set comprising a separate variable condenser connected to eachunit and a common quadrature phase shifter included between the receiverand said Condensers.

4. In a radio receiving system, a multiunit antenna array, a receiverand means for obtaining a plurality of steerable and independent spacefactor directive characteristics included between said array and saidreceiver, said means comprising a plurality of sets of variablereactances, one set for each characteristic, each reactance in each setbeing connected to a different antenna unit, and a plurality of phasecombining networks, a different one for each characteristic, eachnetwork being connected between the receiver and all the reactances ofthe associated set of condensers.

5. In a radio system, a steerable antenna array comprising a pluralityof antenna units connected through separate transmission channels to areceiver, and means for adjusting without change of attenuation thephase relation of the antenna currents included in said channels, saidmeans comprising a plurality of variable condensers, each having a rotorand a plurality of stator plates, said units being connected to separaterotors and the corresponding stator plates being connected together, anda phase combining network having four terminals each connected to adifferent set of corresponding stator plates, and said receiver beingcoupled to said network.

6. A method of securing, in a radio system comprising a multiunitantenna array, a plurality of steerable space factor characteristics forreceiving energy over diverse paths, utilizing a separate variablereactance between each unit and the receiver for each diversity path,which comprises the step of including a network between each unit andthe reactances connected thereto when the number of paths exceeds thenumber of units, including a network between the reactances for one pathand the receiver when the number of units is greater than the number ofpaths, and including the network between each unit and the associatedreactances or between the reactances for one path and the receiver whenthe units and paths are equal in number.

7. A method of receiving radio energy over a first given plurality ofpaths, utilizing an array connected theretowhen the rst given pluralityis larger than the second given plurality, and including a networkbetween the receiver and the corresponding condensers utilized for thesame path when the second given plurality exceeds the rst givenplurality, whereby each condenser and associated network constitute anindependent phase control circuit and a minimum of networks is utilized.

FRANK A, POLKINGHORN.

